The design of an effective wound dressing depends on many factors, including the method of delivery, adherence to the wound, maintenance of a moist environment, minimization of pooling of wound fluids between the tissue and the dressing, prevention of secondary bacterial infection, protection against reinjury, adequate transmission of moisture vapor from the wound bed, no reinjury upon removal of the wound dressing and flexibility of the dressing itself.
Wound dressings prepared from various forms of collagen are known, including collagen sponges, films, powders and enzyme-solubilized gels. We have described these dressings, as well as other medical applications of collagen, in a recent review. Pachence J. M., Berg R. A. and Silver F. H., "Collagen: Its Place in the Medical Device Industry", Med. Device & Diag. Ind., 9: 49-55, 1987. Collagen sponges used as wound dressings are described, for example, in Cioca U.S. Pat. No. 4,412,947 granted Nov. 1, 1983, Berg et al U.S. Pat. No. 4,320,201 granted Mar. 16, 1982, and Artandl, U.S Pat. No. 3,157,524. Non crosslinked or lightly crosslinked collagen sponges fail to provide adequate barriers against bacterial contamination or wound reinjury and resorb too rapidly.
In an effort to eliminate these problems, a dressing has been developed, comprising a collagen compressed foam film laminated, without the use of adhesive, to a thin layer of an inert polymer, as described in McKnight et al., U.S. Pat. No. 3,800,792 granted Apr. 2, 1974. However, collagen films, although providing an adequate barrier against bacterial contamination or wound reinjury, have poor fluid absorption properties and enhance the pooling of wound fluids.
Accordingly, it is among the objects of the present invention to provide an improved collagen matrix/polymer film wound dressing having pre-selected moisture and gas transmissivity characteristics, which greatly control and enhance fluid absorption properties while simultaneously accelerating wound heal time and quality. Additionally, the dressing prohibits maceration and the development of anaerobic bacteria.